The enantio-differentiating hydrogenation of methyl acetoacetate was carried out over a tartaric acid-NaBr-modified reduced nickel catalyst. Nickel hydroxide and nickel carbonate were used as the precursors of the nickel oxide. They were calcined to nickel oxides, then reduced to nickel metal (reduced nickel catalyst). It was revealed that the calcination temperature of the precursors was an important variable for attaining the high enantio-differentiating ability (e.d.a.) of the catalyst. The nickel surface with the least lattice defects would be appropriate for attaining a high e.d.a. (C) 2003 Elsevier B.V. All rights reserved.